This invention relates to a security tag for protecting articles against theft, with at least one, preferably electronically detectable security element and at least one covering layer covering the security element completely and being provided with an adhesive on its side facing the security element. The present invention further relates to a method of protecting articles against theft by means of at least one, preferably electronically detectable security element which is attached to the article to be protected.
Security tags of the type initially referred to as well as corresponding methods for protecting articles against theft are known in the art to secure articles offered for sale or for rent as, for example, video cassettes. Attached to these articles is a security element which may be an electric resonant circuit, for example. When an attempt is made to remove an unpaid article from the salesroom, the security element produces an alarm when carried past detection devices conventionally installed close to the exit. By contrast, when the article is paid for and hence legitimately purchased, the security element has to be removed from the article to prevent the alarm being activated. Alternatively, it is also possible for the security elements to be of the deactivatable type, in which case they only have to be deactivated when the article is paid for and may remain attached to the article. This is particularly useful in connection with rental items because it is not necessary to attach a new security element to the article after the article is returned but enables the still attached security element to be simply reactivated.
Such methods have the disadvantage that the security elements are affixed to the article either visibly or can be easily located by experienced shoplifters. With sufficient criminal energy a potential shoplifter needs only remove the located security element from the article in order to be able to leave the salesroom unnoticed with the now unprotected article. In particular security elements which are adhered to the articles in known manner by means of one or several plastic films are easy to remove.
EP 0 446 910 A1, for example, discloses a security tag comprised of an electronically detectable, deactivatable security element and a self-adhesive coating covering the security element. The deactivatable security element is a soft magnetic strip element onto which rectangular elements of a hard magnetic material are applied. For storage and transportation purposes, this security element is adhered to a peel strip. On its other side the security element is completely covered by a covering layer of paper or plastic, with the covering layer being provided with an adhesive layer on its side facing the security element. When the peel strip is removed, the security element with the then exposed adhesive layer can be adhered to an item to be protected. This known security tag has likewise the disadvantage that it can be detached from the item to be protected relatively easily.